A plate heat exchanger is defined as a heat exchanger having a heat transfer element composed of plates, the plates are the core component of the plate heat exchanger, and the common types of fins include a herringbone corrugation, a horizontal straight corrugation, a ball-shaped corrugation, an oblique corrugation and an upright corrugation, and etc. For enhancing the heat exchanging effect of the plate heat exchanger, the structure of the plate of the plate heat exchanger is continuously developed and improved.
Compared with the conventional heat exchanger, the plate heat exchanger has a very compact structure, the plate heat exchanger is generally made from aluminium alloy, thus is very light, and since the thermal conductivity of the plate is high, the plate heat exchanger has a very high efficiency. Therefore, the plate heat exchanger is highly adaptable, and may be adapted to the heat exchange between various fluids and the phase-change heat exchange with state changing. By arranging and combining flow passages, the plate heat exchanger can be adapted to various heat-exchange working conditions, such as a counter current flow, a cross flow, a multi-stream flow, and a multi-pass flow. Through the combination of a series connection, a parallel connection and a serial-parallel connection of the units, the heat exchanging requirements of large equipments may be satisfied.
Currently, the plate heat exchanger is widely used in air separation plants, petrochemical industry, refrigeration and low temperature field, vehicles and aircraft industries, and other fields.
With the continuous increase of the operating requirement for the heat exchanger, the heat exchanging performance of the plate heat exchanger is also required to be further enhanced. Thus the structure of the plate heat exchanger needs to be optimized, to obtain a plate heat exchanger with a high machining qualification rate, a low production cost and a strong heat exchanging performance.
Since external pipelines of the plate heat exchanger are directly in communication with internal flow passages of the plate heat exchanger, an external fluid directly flows into a distribution flow passage inside the plate heat exchanger, and when a gas-liquid two-phase fluid with low temperature and low pressure enters the distribution flow passage of the plate heat exchanger via the external pipelines, the flow velocity of the fluid may be decreased, and the flow condition of the fluid may be changed with the flow velocity. In the distribution flow passage, the gas-liquid stratification phenomenon of the fluid is aggravated, thus for the fluids flowing into the various flow passages between the plates, some of the fluids contain more gas and some of the fluids contain more liquid, which further decreases the distribution uniformity of the fluid in the flow passages, and reduces the heat exchanging performance of the plate heat exchanger.
Therefore, a technical issue to be addressed presently is to provide a plate heat exchanger, to prevent the gas-liquid stratification of fluid from being aggravated and improve the distribution uniformity of the fluid in the flow passages.